If you think there is an easy solution that professionals who are paid to deal with these things are not seeing, chances are that there is something about the issue that you are ignorant of.
Your solution presumes people can still reconnect. What happens if the power goes out? Should you be punished the same as a rage quitter because you cannot immediately rejoin?
And what of those who were recently utilizing an exploit to avoid the respawn timer by disconnecting and reconnecting? Should they receive the same reduced punishment as the person who briefly experienced a legit connection issue?
No. The only fair way to handle this is to treat all leavers the same, regardless of the reasons why they left the match, or if they return.